KABUL, Afghanistan (AP) — A man leading the Taliban side of peace talks with the Afghan government was an impersonator, an Afghan close to the negotiations said Tuesday, an embarrassing revelation for Afghan officials who have promoted reconciliation efforts as the best chance for ending the war.

Quickly moving to do damage control, President Hamid Karzai dismissed the reports as “propaganda,” saying neither he nor any other members of his government had ever met with a man named Mullah Akhtar Mohammad Mansour — one of highest ranking members of the Taliban council leading the insurgency.

The report about the impostor first appeared in The New York Times and The Washington Post.

An Afghan familiar with the reconciliation efforts confirmed that a delegate claiming to be Mansour “was a fraud.” He spoke on the condition of anonymity so as not to jeopardize his contacts with both sides.

NATO, which was reportedly deeply involved in the meetings and purportedly flew the impostor to Kabul, did not immediately comment on the reports.

Mansour, a former civil aviation minister during Taliban rule, is a senior member of the Taliban’s ruling council in the Pakistani city of Quetta. That council, or shura, is run by Taliban leader Mullah Mohammad Omar.

If confirmed, the claims that he was not really involved would be a blow to the Afghan government’s push to find a political resolution to the nine-year-old war. It also raised questions about the credibility of some NATO officials who have said they facilitated contacts between Taliban figures and Afghan officials.

According to the reports, the impostor met with Afghan and NATO officials three times — including once with Mr. Karzai — before they discovered he was not Mansour. He was purportedly paid to attend.

Mansour was a well-known Taliban leader and had a high profile job in the movement’s Cabinet. It is not clear why officials would have had such a difficult time identifying him. There are a number of former Taliban in parliament and in the 70-member High Peace Council recently formed by Mr. Karzai to find a political solution to the insurgency. It was reported that the man was believed to be a shopkeeper in Quetta.

Although quite senior in the Quetta Shura, Mansour was not promoted to second-in-command of the Quetta shura following last February’s arrest in Pakistan of Abdul Ghani Baradar. The AfghanTaliban’s No. 2 leader was arrested in a joint raid with the CIA.

Mansour was passed over in favor for Maulvi Zakir Qayyum — a former Guantanamo detainee. Released into Afghan custody in 2007, Qayyum was freed four months later and rejoined the Taliban.

In Pakistan last week President Obama’s special representative to Afghanistan and Pakistan, Richard Holbrooke, played down reports about that senior Taliban leaders were holding talks with the Afghangovernment.